This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Gene-modified mice have served as models of disease and tools for investigative research into the function of genes for the past 30 years. Despite their widespread use, the techniques and equipment required to produce these mice remain specialized. The Transgenic and Gene-Targeting Facility, therefore, supports the research of COBRE investigators by creating gene-modified mice and providing embryo services. The Core generates transgenic mice by pronuclear injection, chimeric mice by injection of blastocysts and targeted embryonic stem cells by electroporation, as well as providing support services such as genotyping and sperm cryopreservation. A centralized core facility such as ours negates the need for each laboratory to expend the time and money required to become proficient in embryo handling and transgenic mouse production, thereby accelerating research.